Instrument for drafting



.April 9; 19290 J. A. NELL INSTRUMENT FOR DRAFTING Filed May 19, 1927 z .e w n Q l o 3 j W ,m W. m 1U WIM ullmwm Ll. M n H @j W m Hl m uw Q m. m mg m @ITI m M- m Mw b N v1 ,A .WM W/ l V 1m w. IH u l b .wr/m, w www w n H \H\ wif W m fw mm1, m n|| M mw wh/.Q I |m mlm mw llesll Ilan \h m\ u H H. W m w mw V w @ma M m .l mi wm Q NAVY m Nw .m H H mmm im im @ma @www N k w @A w n, fm M mlm HGM w 1 1m m@ MH. |H W mow ci Qu oo f o vw/ L en m. /lm www HI lll Wa ,f M H2 H M W Y l Mm ml. o H l mw Y. 1 o 5 P n .N .-Nvv MNM A u m w mm. o r E n mw im .w

Patented pr. 9, 1929,

para

JAMES A NELL, 0F NEW BRITAIN, CONNECTICUT.

INSTRUMENT FOR DRFTING.

Application filed Hay 19,

This invention relates to instruments for drafting and of the type disclosed in Letters- Patent, No. 1,492,893, issued to me May 6th, 1924. i

The obj ects of the present invention are to provide a simple instrument free of movable parts the use of which will facilitate the drawing of lines in parallel or any desired angular relation; to provide in such an instrument protractor elements whereby a given angle may be quickly and accurately measured or lines drawn to deline a desired angle; to provide means whereby certain xed or standard angles may be easily marked; to provide means whereby small circles may be accurately formed without the use of a compass, and to generally enlarge the range of usefulness of the device. These stated objects and other objects which will hereinafter incidentally appear are attained in such an instrument as is illustrated in the accompanying drawing, and the invention resides in certain novel features which will be particularly pointed out in the .appended claim.

The drawing is a plan view of an instrument embodying the invention.

The device consists essentially of a rectangular frame having end members 1 and 2 and side members 3 and 4, each of said members having parallel edges. rhe frame may be constructed of an integral thin metal plate faced with Celluloid or the like, or it may be made from strips secured together by anyl convenient means, the total thickness being from .035 to .059 of an inch so that, while the instrument will be durable, weight and'bulk will be avoided. At the outer corners of the frame, narrow thin L-shaped strips 5 are secured upon its face so as to reenforce the frame and also prevent it from slipping under a s.iT-square when used therewith.

Each of the members 1, 2, 3 and 4 is formed with a longitudinal slot 6 extending parallel with the sides of the member and so located that the member is divided into an outer relatively narrow rail and an inner relatively wide rail. n the wider rail of each end member 1, 2, is a longitudinalslot 7 parallel with the slot 6 but narrower and having one end located in alinement with the inner edge of the side member 4 and the opposite end disposed near an end of the slot 6 in the member 3 and curved slightly toward the same, as shown at 8. 1n the wider rail of said member 3 are alined longitudinal slotsl 9 which 1927. Serial No. 192,668.

have their inner ends near the center of the rail and their outer ends near the curved ends of the slots 7, a short web 10 separating the inner ends of the slots and similar webs 11 separating their outer ends from the slots 7. rlhe ends of the slots 9 are also so arranged relatively to the curved ends of the slots Z that they may be marked with graduaticns giving a continuous scale reading. Along both edges of all the members 1, 2, 3 and 4 are scales, indicated at 12, graduated in inches and fractions of inches and like scales are inscribed alongthe sides and endsof the slots 6, as indicated at 13, while along the outer sides of the slots 7 and 9 are scales 14 graduated in degrees of a circle and fractions thereof and along the inner sides of said slots are graduations 15 marking live degree intervals. Preferably, the notations of these scales 14 and 15 run in'opposite directions, the aero point of the scale l5 being at the web 10 and the zero point of the scale 14 being on the line of the inner edge of the member 4 extended.

In the wider rail of the member 4 are arcuate slots 16 arranged in a series with their ends overlapping so that they constitute a protractor with the degree scales 17 merging to furnish a continuous reading. At opposite sides of the protractor slots 16 are openings 18, 19, of a general triangular form and each having two straight sides 2O disposed at an angle of 120D tov facilitate drawing two sides of a heXagOn. At the base of the openig 18 is an arcuate projection 21 While from the base of the opening 19 projects a point 22 the sides of which define an angle of 82 for uscin drawing the under side of a flathead screw, and circular holes 23 are formed through the device at various points to provide ror drawing small circles without a compass. These holes have diameters, varying by 1/64 of an inch, from 8/64 of an inch to 13/32 of an inch and the identifying designations are placed on the face and also on the back of the instrument and the identifying designations in decimal equivalents of an inch are placed on the back of the instrument to avoid excessive crowding on the face thereof, the designations of the angles 82 and 120 being placed on the back for the same reason. rEhe notations for the scales of linear measurement are carried from the center to both ends of the scale so that the measurement may be read in the most convenient 'way in any given case.

The instrument will generally have an outside measurement ot 6 x 9 inches but it may be made in various sizes, although the proportions` will always be the saine. The outer rails are one-half inch wide and the inner rails are three-fourths ot' an inch Wide While the slots 6 are one-fourth of an inch wide thus making it possible to draw parallel lines 1/{,1,/,3/,lorlhinches apart with any niember of the instrument with a single setting'. To compensate for the thickness ot' the pencil mark and attain accuracy in the measuren1ents.the rails are about .015 ot an inch short of their rating while the slots are a like amount in excess ot their rating.

The instrument is used on a drawing board in connection with a T-square in the same manner that a triangle is used, and it will be obvious that any edge ot any member of the instrument may be used for drawing a line. Lines at right angles may be drawn with` the corners of the instrument within its capacity and by shitting the instrument quadrangles may be quickly` constructed. Angles other than right angles may be drawn. Let it be assumed that a line is to be drawn upwardly and inclined to the right with respect to the base line. The instrument is so placed that the inner edge of the member 4 is on the base line and the zero pointot the inside rail is at the point where the lines are to intersect.

A pencil dot is placed at said point and another dot is placed at the proper ldegree notation, on the member 2 whereupon the instrument is moved until one edge alines with the two dots, the required line being then drawn in ari-obvious manner. Let it be assumed that an inclined line is to be drawn upwardly to the left from a base line. is placed as just described and then moved toward the positionot the line to be drawn,

the base line being observed through the slot` 7 in the member 2 and the zero point of the member 4 being kept at the point ot intersection with the base line. When the baseline registers With the proper degree notation the instrument will be in position to locate the line to be drawn, and the base line should register with the same notation in the minor protractor there thus being three points of alinement. The desired line may then be drawn.

AIt is to be understood that the accompanying drawings are illustrative only and not restrictive and that the details of the instrument may be varied Without departing from the spirit or scope ot' the invention as the same is defined in the following claim.

Having fully described my invention what I claim as new and desire to secure by Letters- Patent, is

A drafting instrument comprising four members joined to form a rectangular frame, three members of which are provided with longitudinal slots and have degree graduations along the edges of said slots forming a major protractor, and the Jfourth member having an arcuate slot with degree graduations along the edge of the saine forming a minor protractor, all said graduations radiating from a connnon center on the fourth niember of the trame.

In testimony whereof, I have signed this specification.

JAMES A. NELL.

The instrument 

